Manometer system



Dec. 24,1957 J. c. STEVENS MANOMETER SYSTEM Filed April 29, 1954INVENTOR. JOHN C. STEVENS WIWMM ATTORNEYS United States Patent MANOMETERSYSTEM John C. Stevens, Portland, 0reg., assiguor to Leupold &

Stevens Instruments, Inc., Portland, Oreg., a corporation of OregonApplication April 29, 1954, Serial No. 426,490

1 Claim. (Cl. 73401) This invention relates to manometer systems, andparticularly to registering or recording manometer systems adapted foruse in pressure measurements of turbid liquids, especially flowingturbid liquids where pressure is a function of velocity and quantityflow.

In prior manometer systems adapted for use in connection with turbid ordebris carrying liquid, such as sewage or liquid industrial wastes, ithas been found necessary to provide a separation chamber between theturbid liquid and the manometer tube in order to keep the tube clean.The separation chamber conventionally has included a diaphragm orsimilar member which functions to separate the manometer liquid from theturbid liquid. The diaphragm has disadvantages in that it makes thesystem less sensitive than those systems wherein the pressure liquid isclean or clear and no separation chamber need be employed, andfurthermore the diaphragm is diflicult to clean and in general raisesconsiderable maintenance problems.

It is a main object of the present invention to provide a manometersystem adapted to be used in connection with turbid liquids, wherein theneed for a separation chamber is eliminated and direct communicationbetween the turbid liquid and the manometer tube by means of an openconduit is provided. This advantageous arrangement is made possible bythe provision of a periodic flushing means which is operable toperiodically flush the conduit free of polluted liquid with a higherpressure clear liquid, at a time prior to that at which the pollutedliquid would reach the manometer tube, and to replace such pollutedliquid with clear liquid.

It is a further object of the present invention to pro vide a manometersystem of the type just set forth, wherein a valve arrangement isprovided for preventing the higher pressure flushing liquid fromalfectiug the level of the liquid in the manometer, to thus avoid notonly highly erroneous records, but also to-avoid overworking andpossible damage to the portions of the manometer system operable inresponse to changes in the liquid level.

A more particular object of the present invention is to provide amanometer system of the type just set forth immediately above, whereinthe operation of the flushing means and the valve arrangement iscontrolled by the recording mechanism of the manometer system.

It is another object of the present invention to provide a recordingmanometer system having liquid level sensing means dependent for itsproper operation upon the maintenance of substantially constant lighttransmitting properties of the manometer liquid, the system including anopen conduit communicating the turbid liquid with the manometer liquid,the system further including periodic flushing means operable to flushthe conduit free of the liquid therein, including the polluted portionsthereof, prior to the time that polluted liquid would enter themanometer tube. Thus the light transmitting properties of the manometerliquid may be maintained constant.

It is a still further object of the present invention to provide amanometer system as described immediately above wherein the properoperation of the system is dependent upon maintaining the manometerliquid clear for proper transmission of a light beam therethrough.

Various other objects of the present invention will be apparent from thefollowing description taken in connection with the accompanyingdrawings, wherein:

Fig. 1 is a schematic view of a manometer system embodying the conceptsof the present invention;

Fig. 2 is a schematic wiring diagram of the system;

Fig. 3 is a schematic View in plan, showing the photocell setup of arider, the figure illustrating an equilibrium condition; and

Fig. 4 is a schematic view in side elevation of the Fig. 3 structure.

Referring to the accompanying drawings wherein similar referencecharacters designate similar parts throughout, there is disclosed inFig. 1 a sewage line 9 having a restricted portion at 11 providing aVenturi section. Flowing through the sewage line is sewage which may becharacterized for the purpose of this invention as turbid or debriscarrying liquid. Instead of sewage, line 9 could contain other solids orgas carrying liquids known as industrial wastes. In any event, suchliquid may be considered as containing diffusible molecules capable ofcreating a turbid condition in clear water, that is, darkening, cloudingor otherwise altering or impairing the light transmitting qualities ofthe clear liquid. Such turbid or debris carrying liquid may also beconsidered as containing buoyant and nonbuoyant light reflecting,retracting or absorbing particles, elements or matter. For conveniencein description, gas or air bubbles may be considered as refractingparticles, elements or matter.

Communicating with sewage line 9 at the restricted portion thereof is aconduit 13, and communicating with line 9 at a place upstream of suchrestricted portion is a conduit 15. Each of the conduits is shown ashaving considerable length, for a reason to appear hereinafter, and alsoincluding a horizontal run portion which functions to substantiallybring to a halt the travel of buoyant particles along said conduits in adirection away from line 9. Each run portion may be arranged to extendslightly downwardly in a direction from left to right, as the parts aredepicted in Fig. l, to make certain that no buoyant travel occurs. 7

Conduits 13 and 15 are shown as having vertical end portionscommunicating respectively with the lower ends of the legs of aninverted U-shaped transparent manometer tube 17. It will be evident thatthe conduits 13 and 15 will normally comprise piping of various forms,whereas the manometer tube will normally be formed of glass tubing. Agaseous medium under pressure may be provided in the upper portion oftube 17, and thus the tube may be considered as closed. A suitable valve18 is connected to the upper portion of tube 17 to permit a gaseousmedium to be pumped into the tube.

Provided in the upper ends of conduits 13 and 15 are solenoid controlledvalves 19 and 21, respectively, said valves being biased toward closedpositions but being normally energized to be open. Connecting the upperends of conduits 13 and 15 at places below valves 19 and 21 is a conduitsection 23. Disposed in conduit section 23 are solenoid controlledvalves 25 and 27, which are biased toward closed positions and arenormally de-energized and thus normally closed. Between valves 25 and 27is a conduit 29 communicating with conduit section 23 and leading to andcommunicating with a clear liquid or water tank 31. Provided in conduit29 between the tank and conduit section 23 is a normally inactiveelectric motor driven pump 33. Pump 33 may be eliminated by positioningtank 31 sufficiently high to achieve the desired pressure. For supplyingthe tank with clear water, a supply pipe 35 is provided, there being afloat controlled valve 3. 37 adjacent the outlet of pipe 35 and operableto close the pipe during normal operation of the manometer system, atwhich time the water level in the tank will be high.

Slidable along the left'hand leg of manometer tube 17 is a photocellrider 41 and slidable along the right-hand leg of manometer 17 is asecond photocell rider 43. These riders are of the general typedisclosed in my prior Patent No.- 2,376,459, and are connected byflexible means 45 to the opposite ends of a differential unit 47. Theriders are electrically connected to control the operation of electricmotors 49 and 51, respectively, in a manner to bc presently indicated.Connected to the center of the difierential unit is a flexible Shaft 53leading to a recorder 55 to control the position of a pen 57. Pen 57makes a record on a circular chart which is driven by a conventionalelectric motor operated clock mechanism within the recorder, suchmechanism being indicated at 61 in Fig. 2.

In my prior Patent No. 2,376,459, the riders are adapted for operationwith a manometer tube carrying an opaque liquid. Each rider projects abeam of light across the surface of the opaque liquid toward verticallyoffset photocells, the rising and falling opaque liquid being adapted tocut off or permit momentary unnatural light reception by the photocellsto control the associated motors in a manner, as indicated in saidpatent, to cause the riders to follow the liquid levels in theirrespective tubes.

In the present invention, similar rider-following movement may beattained, although clear liquid occupies the manometer tube, by makinguse of the different refractive effects of liquid and air on the lightbeam. Figs. 3 and 4 schematically show the idea employed, where anequlibrium condition is shown. A light beam from source A is refractedby the meniscus of the liquid in tube 17 and thus passes above thephotocells B and C, which are disposed at the same level. In practice, aprism, see 3, is provided for each photocell, because the photocells aretoo bulky to be conveniently placed side by side for direct reception ofthe light beam.

Photocells B and C are connected in a circuit, not shown, identical tothat disclosed in Fig. 3 of Patent 2,376,459, except that each of thephotocells i3 and C is connected by a normally open switch, similar toswitch 53 in said patent, to the associated motor winding. Thus, underequilibrium conditions, the associated motor is deenergized because thelight beam, as above mentioned, 1

would then be effective to cause the associated motor winding to becomeenergized so that the motor rotates in a direction to elevate the rideruntil the meniscus again intercepts the light beam. On the other hand,if the liquid level should fall, the light beam would level oil andstrike the prism for photocell C, as shown in full lines in Fig. 3.Photocell C would then be effective to cause the associated motorwinding to become energized to cause the motor to rotate in a directionto lower the associated rider until the meniscus again intercepts thelight beam.

It is pointed out at this time that the operation of the photocell meansof the riders will become erratic if the light beam is substantiallydiminished in intensity or misdirected, such as might be caused byforeign matter polluting the clear manometer liquid and collecting onthe walls of the manometer tube. it will be noted that air and gasbubbles in the manometer liquid would retract the light difierently thanwould liquid without such bubbles. Also, such air and gas bubbles wouldtend to diminish or alter the pressure in the upper end of the manometertube, particularly if the upper end is filled with a gaseous mediumunder pressure. Such alteration would obviously affect the liquid levelsin the manometer legs.

Referring to Fig. 2, the electric motor driven clock mechanism of therecorder 55 is indicated at 61 in driving relation to a cam 63.Associated with the cam is a normally open switch 65 operable whenclosed to control the supply of electrical energy in a predeterminedmanner to solenoid valves 19, 21, 25 and 27 and electric motor drivenpump 33, provided a pump is employed.

The electric circuit depicted in Fig. 2 includes supply conductors 67and 69, conductor 69 being the ground conductor. Clock motor 61 isconnected across the supply conductors as shown to be normally operatingso as to drive cam 63 at a slow rate of speed and also to drive thechart in the recorder. A master switch, not shown, may be actuated tode-energize the electrical system when desired. Switch 65 is connectedat one side to conductor 67 and at its other side to a solenoid winding71, the other side of such winding being connected to conductor 69 asshown. The solenoid winding 71 controls the operation of a movablesolenoid element 72, which is mechanically connected to the switch arms73 and 75 of a pair of single pole, double throw switches. Switch arm 73is connected to conductor 67 by a conductor 77, and is shown inengagement with the contact of a conductor 79, the latter beingconnected to solenoid valve 19, which is connected to ground as shown.Switch arm 73, when thrown clockwise as the parts are depicted in Fig.2, is adapted to be brought into engagement with the contact of aconductor 81, the latter being connected to solenoid valve 25, which isconnected to ground as shown. The electric motor operated pump 33, ifemployed, is connected in parallel with solenoid valve 25 as shown.

Switch arm 75 is connected by a conductor 82 to supply conductor 67 andin the position shown is disposed in engagement with the contact of aconductor 83, the latter being connected to solenoid valve 21, the otherside of which is connected to ground as shown. Switch arm 75 when throwncounterclockwise is adapted to engage the contact of a conductor 85, thelatter being connected to solenoid valve 27, which is connected toground as shown.

Operation Since conduits 13 and 15 are open so as to place the manometertube in communication with sewage line 9, polluting substances or matterin the sewage liquid in line 9 may travel into conduits 13 and 15 towardthe: manometer tube. Such travel may occur. for instance, because of thediffusion of turbid creating molecules in the sewage liquid into theliquid within the conduits; or because of the bouyancy of bouyantparticles, elements or matter in the sewage liquid entering theconduits, such particles or elements including solids, or semisolids, oreven liquids such as oil, and also including air or gas bubbles; orbecause of the etfect on particles by the rising and falling motion ofthe manometer liquid; or because of the effect of convection currentsunavoidably occurring in the conduits; or for any combination of theabove effects.

For purposes of explaining the operation of the system, it is assumedthat a flushing operation is just about to commence so that the liquidin the conduits 13 and 15 is shown as being polluted up to a point shortof conduit section 23, and cam 63 is shown in a position as just aboutto contact switch 65. Closing of switch 65 causes arms 73 and 75 toswing clockwise from the positions shown, to thus de-energize previouslyenergized solenoid controlled valves 19 and 21 to allow them to close,and to energize previously de-energized solenoid controlled valves 25and 27 to cause them to open. Also, if a pump 33 is employed, it will beenergized, said pump having an output pressure higher than that in line9, and thus clear water from tank 31 is pumped into conduit section 23from which it travels into conduits 13 and 15 and moves downwardlytherein because the closed solenoid valves 19 and 21 prohibit upwardmovement of such liquid. Thus, liquid in legs 13 and 15 is forced intoline 9.

The lobe on cam 63 is designed to have a circumferential extensioncorrelated to the rate of travel of the cam so that switch 65 is closedfor the required period of time; that is, long enough so that pump 33will pump suflicient clear liquid into conduits 13 and 15 as todischarge all of the conduit liquid from said conduits, including thepolluted liquid portions thereof, and replace the same with clearliquid. In fact, it is contemplated that clear liquid will be suppliedby pump 33 in such quantities and at such pressure that it rushesthrough conduits 13 and 15 at a fairly high velocity so as to have acleansing effect on the walls of the conduits to remove debris orpolluting substances therefrom. As the pump removes water from tank 31,float valve 37 operates to supply additional quantities of clear waterto the tank to eventually bring the level back to normal.

When the lobe of cam 63 leaves switch 65 the switch opens causing valves19 and 21 to open, valves 25 and 27 to close, and pump 33 to stopoperation, to thus place the system back in condition for normaloperation. The operation of clock motor 61 is so correlated to thetravel time of the polluting substances from the line 9 to the conduitsection 23 that cam 63 once again engages and closes switch 65 to causeanother flushing operation to commence prior to polluting substancesreaching conduit section 23.

It is pointed out that during the flushing operation the high pressureclear liquid in the conduits 13 and 15 has no effect on the liquid levelin the legs of manometer tube 17 because of closed valves 17 and 21, sothat the riders 41 and 43 remain stationary. Thus, although the recorderdoes not record pressure changes occurring during the flushing period,the flushing period is relatively short and the resulting record is muchmore accurate than that which would be produced were the high pressureliquid permitted to elevate the liquid levels in the manometer legs.

It is evident that if the polluting substances are to be kept fromreaching conduit section 23, that the period between supply operationsmust be made less than the travel time of the polluting substances fromline 9 to conduit section 23. The travel time of the pollutingsubstances is equal to the ratio of the length of the conduit to therate of travel of the polluting substances. The rate of travel of thepolluting substances depends primarily on the kind and types of matterin the sewage line and to some extent on operating conditions. Thetravel effects due to buoyancy can be considerably decreased or entirelystopped by providing horizontal run portions in the conduits, orportions which incline slightly downwardly in a direction away from line9, or even inverted U-shaped bend portions. However, in someinstallations this may not be desirable or possible, and thus thebuoyancy effects must be taken into account in some situations. However,the rate of travel of the polluting substances, which primarily has tobe taken into account, is caused by the diffusion of turbid creatingmolecules into the clear liquid in the conduits 13 and 15. Also to beconsidered are the effects of convection currents, and rising andfalling liquid levels in the manometers.

For any particular system, the travel time may be readily determined bymaking a trial run and noting when the polluting substances reach themanometer tube. It will be normally more economical to provide conduits13 and 15 of considerable length to thus increase the periods betweensupply operations. For instance, in one installation a conduit length ofapproximately twenty feet was employed, and it was found that a periodof as long as six hours between flushing operations could be tolerated.In this system a flushing period of one minute was found satisfactory.

By the present invention, a manometer system has been provided whereinthe manometer tube may be placed in direct communication with a sewageline, thus eliminating the necessity for separation chambers and thelike and their accompanying disadvantages. Specifically, the concept ofthe present invention is particularly adaptable to a system wherein thesensing means includes photocells dependent for proper operation uponsubstantial constant intensity and proper direction of a beam of lightprojected at least in part through clear manometer liquid.

Having described the invention in what is considered to be the preferredembodiment thereof, it is desired that it be understood that theinvention is not to be limited by the specific details shown unless theyconstitute critical features of the present invention, all of which willbe apparent by reference to the following claim.

I claim:

In a manometer system, an upright transparent manometer tube, a line forturbid liquid under pressure, a conduit connected at one end to the lineand connected at its other end to the lower end of said tube, acontinuous column of water entirely filling said conduit and extendingupwardly into and partially filling said manometer tube and initiallybeing clear, said column being immediately and directly responsive tochanges in pressure in said line to shift along said conduit to cause animmediate and direct change to the level of the column of water in themanometer tube, clear water supply means connected to said conduit, saidclear water supply means being operable to supply water at a pressurehigher than that of the turbid liquid, means controlling said supplymeans periodically operable to supply liquid from said supply means tosaid conduit a quantity of clear water, a valve in the conduit betweenthe place of communication of said supply means with said conduit andthe level of said column of water in said tube, means for closing saidvalve during the time that clear water is supplied to said conduit fromsaid supply means, and means responsive to changes in the height of thewater in said tube for giving an indication of such changes, saidresponsive means including a housing surrounding said tube, means forprojecting a beam of light through said tube along a predetermineddirection, first and second light responsive means on said housingpositioned so that when said beam of light passes through the meniscusof said column of water the beam will be deflected along a path notfalling on either of said light responsive means, said projecting meansdirecting said light so that said beam of light enters said tube along apath other than along a diameter of said tube so that when said beampasses through clear water, such as when the water level in said tuberises, the beam will exit from said tube along one path and when saidbeam passes through air in said tube, such as when the water level insaid tube drops, said beam will exit from said tube along another path,said first light responsive means being positioned to intercept saidbeam when said beam is directed along said one path and said secondlight responsive means being positioned to intercept said beam when saidbeam is directed along said other path, and motor means controlled bysaid first and second light responsive means for raising said housingwhen said first light responsive means receives light and for loweringsaid housing when said second light responsive means receives light tothereby maintain said housing at the place where said beam of lightpasses through the meniscus of said column of clear water, said clearwater supply means functioning to prevent said clear water from becomingturbid which would interfere with the proper operation of saidresponsive means.

References Cited in the file of this patent UNITED STATES PATENTS2,058,654 Allton Oct. 27, 1936 2,205,254 Gulliksen June 18, 19402,240,988 Hertel May 6, 1941 2,337,921 Petroe Dec. 28, 1943 2,376,459Stevens May 22, 1945 2,553,918 Hofer May 22, 1951 2,573,006 Good Oct.30, 1951 2,604,778 Marquardt July 29, 1952

